碘量法测定葡萄糖含量的小量化与绿色化研究与实践

碘量法是测定葡萄糖含量的常规分析方法,也是定量分析化学实验常开设的综合性实验。对传统教材中的碘量法测定葡萄糖含量实验内容进行了小量化改造,并研究了氢氧化钠用量及滴加速度、反应温度、放置时间、酸的用量、滴定震荡速度及淀粉加入时刻等影响因素对碘量法测定葡萄糖含量的影响。实验结果表明,小量化滴定能够达到常量滴定分析要求的精密度与准确度,可大幅度降低实验消耗、节省实验经费80%以上,使学生树立绿色化学思想和环境保护意识,全面提高人才的培养质量和效益。     

漫反射光谱法测定还原糖

通过测定还原糖与斐林试剂反应生成的Cu2O，建立测定还原糖的漫反射光谱分析方法。该方法具有操作方便，灵敏度高，试剂用量少等优点。还原糖在20～120μg范围内呈良好的线性关系，用于实际样品测定，结果满意。     

碘量法测定水中溶解氧

针对碘量法中反应试剂硫酸锰溶解缓慢、实验周期较长并伴有大量沉淀的现象,进行了氯化锰和硫酸锰对比实验,结果证明,采用氯化锰替代硫酸锰作反应试剂较好.对影响碘量法测定结果的因素进行了研究,控制适量的氯化锰和硫酸加入量.可提高碘量法的准确度.     

硫酸铵中氮含量的电位滴定检测

建立一种酸碱电位滴定法直接测定硫酸铵中氮含量的方法。样品溶解后,可直接用氢氧化钠标准滴定溶液进行滴定。为了保证检测的准确度,分别使用硫酸铵高纯试剂和邻苯二甲酸氢钾基准试剂对氢氧化钠标准滴定溶液进行标定,并对标定结果进行比较,两种方法基本无差异。同时,通过适量硫酸的加入避免了样品中游离硫酸对检测结果的影响。该方法检测速度快、检测精度高、绿色环保、易于控制,非常适合于硫酸铵中氮含量的检测。将本方法与蒸馏后滴定法(仲裁法)检测结果进行比较,两种方法无显著性差异。采用本方法测得氮含量的加标回收率为99.9 %-100.3 %,相对标准偏差(RSD,n=5)为0.03 %-0.05 %。分别使用实验方法和蒸馏后滴定法测定不同样品的氮含量,结果相吻合。     

原子吸收法间接测定生物样品及食品中的还原糖

对于糖的测定,目前国内外均采用斐林法、碘量法、分光光度法及离子选择电极法等。本文研究了用原子吸收法测定被糖还原的 Cu_2O 的量间接测定还原糖含量的实验条件,并用于葡萄糖中间体、成品、桔子汁、蔬菜、酱、醋、蜂蜜及人体血液等样品中还原糖含量的测定。其线性范围0.05—3mg,回收率98—101%,变动系数1%。本工作是在 pH约为11的碱性介质中,以还原糖将柠檬酸铜络合物     

酸量法及碘量法测定氧化葡聚糖的醛基

通过高碘酸钠氧化葡聚糖,制备不同氧化度的葡聚糖,采用酸量法和碘量法测定其醛基含量,但所得结果差异大.结合葡聚糖的氧化机理,以甘油的氧化反应结果作为对照,对借助化学滴定分析的酸量法和碘量法所得数据的差异性进行了分析.结果表明这种差异是由葡聚糖氧化存在的中间反应及其分支结构造成的,当高碘酸钠与葡聚糖的糖单元的物质的量比控制在2以内,操作简单的酸量法所得结果是可靠的.     

氯化亚铜中亚铜及高价铜盐含量的示波滴定

１引言氯化亚铜含量的测定在国家标准分析方法中是根据亚铜离子能使Ｆｅ３＋还原为Ｆｅ２＋，然后以邻菲啉－硫酸亚铁络合物作指示剂用高铈盐进行滴定。氯化亚铜中高价铜盐测定则利用高价铜盐能溶于５ｍｏｌ／Ｌ乙酸．而亚铜盐不能溶解进行分离，然后再用碘量法进行测定，手续十分麻烦。本文根据ＣＵ（Ⅰ）与四苯硼钠定量生成沉淀，用示波滴定法中的四苯硼钠法进行氯化亚铜含量的测定，高价铜盐被抗坏血酸还原，再用四苯硼钠法进行滴定，差量法计算出高价铜盐含量，操作简便，终点直观，测定结果准确。２实验部分２．１主要仪器与试剂ＬＳ－…     

氯化四唑蓝比色法测定微量2-脱氧-D-葡萄糖

氯化四唑蓝是还原糖的灵敏试剂,可在加热的碱性溶液中与还原糖反应,生成不溶性的三苯福尔马散红色沉淀。2-脱氧D-葡萄糖虽也属还原糖,但还原性显著减弱。我们试用四唑蓝比色法对2-脱氧-D-葡萄糖进行了微量测定。改进了操作步骤,提高了灵敏度,而且数据稳定,重现性好。 (一)试剂     

高精度蠕动泵式称量滴定装置及称量滴定方法

滴定分析法是将一种已知准确浓度的试剂溶液,滴加到被测物质的溶液中,直到所加的试剂与被测物质按化学计量定量反应为止,根据试剂溶液的浓度和消耗的量,计算被测物质含量的方法。滴定分析法可分为容量滴定法和称量滴定法。目前实验室滴定分析普遍采用容量滴定法,因其所用设备简单、操作方便、迅速,滴定精度可达0.1%,被广泛用     

以金纳米粒子为指示剂的法扬司法测定氯离子

将纳米材料引入到滴定分析法中,利用柠檬酸钠还原氯金酸法制备了带负电荷的纳米金,然后,以纳米金为吸附指示剂,利用纳米金局部表面等离子体共振特性来确定滴定终点,从而建立了检测氯离子的新型法扬司法。研究表明,该方法在毫摩尔级可准确测定氯离子,并且废液可通过配位反应、沉淀反应和氧化还原反应,将金和银回收再利用,从而降低成本并减少污染。通过本实验的实践,使学生接触到学科的前沿领域,激发学生对科学研究的兴趣,培养学生的科研探究能力,推动绿色化学在本科教学中的应用。     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.